Angular NgRx - 如何在我的模板 html 中查看商店中的对象？

Question

Hey i have object in store and i want to view the object in the template.

My Ts File:

import { Component, OnInit } from '@angular/core';
import { Observable } from 'rxjs';
import { Store } from '@ngrx/store';
import { Comment } from '../../models/comment.model';
import { User } from '../../models/user.model';
import { AppState } from '../../app.state';

@Component({
  selector: 'app-ngrx-get-data',
  templateUrl: './ngrx-get-data.component.html',
  styleUrls: ['./ngrx-get-data.component.scss']
})
export class NgrxGetDataComponent implements OnInit {
  comment$: Observable<Comment[]>;
  userDetails$: Observable<User>;

  constructor(private store: Store<AppState>) {
    this.comment$ = this.store.select('comment');
    this.userDetails$ = this.store.select('user');
  }

  ngOnInit() {
  }

}

My template:

<div style="margin: auto;">
<h1 style="text-align: center;">USER DETAILS FROM API</h1>
<li *ngFor="let item of userDetails$ | async ">
  <ul>{{item}}</ul>
</li>
</div>

My Error in console:

ERROR Error: Cannot find a differ supporting object '[object Object]' of type 'object'. NgFor only supports binding to Iterables such as Arrays.

I try this and its not work:

<h1 style="text-align: center;">USER DETAILS FROM API</h1>
<li *ngFor="let item of userDetails$ | keyvalue">
  <ul>{{item.key}} {{item.value}}</ul>
</li>

Image if my state:

Answer 1

What you need is to combine async and keyvalue pipes together. Also the order of the pipes important :

<h1 style="text-align: center;">USER DETAILS FROM API</h1>
<ul *ngFor="let item of userDetails$ | async | keyvalue">
  <li>{{item.key}}: {{item.value}}</li>
</ul>

Here's a demo stackblitz of this code: https://stackblitz.com/edit/angular-1rj8sc

Answer 2

This is the correct way to do it:

<div style="margin: auto;">
    <h1 style="text-align: center;">USER DETAILS FROM API</h1>
    <ul *ngIf="userDetails$ | async as details">
        <li *ngFor="let item of details">{{item}}</li>
    </ul>
</div>

First you need to let Angular subscribe to observable using async pipe, use that within an *ngIf otherwise it will try to iterate over something that does not exist yet. Next use *ngFor to create multiple <li> elements, not <ul>

Answer 3

If your slice of state 'user' is normalized and stored as an object with the key: object structure, you'll need to convert that to an array to iterate over it in the template.

You can easily convert it to an array with something like this

  private userDetails: User;
  constructor(private store: Store<AppState>) {
    this.comment$ = this.store.select('comment');
    // Use Object.values() to convert to an array with all the values of that object
    this.userDetails$ = this.store.select('user').subscribe(userDetails => {
     this.userDetails = Object.values(userDetails);
    });
  }

  // Then

  <li *ngFor="let item of userDetails">
    <ul>{{item}}</ul>
  </li>

Though it's hard to know exactly what's going on without seeing the data structure.

Some other notes: If userDetails is just a single object, and you want to iterate over each property, and get the key and value, use Object.entries()